ARP Head Bolt Kit for Mini Cooper 1.6L R53 Supercharger Pro Series

ARP head bolt kit. It is for good reason that virtually every top professional engine builder relies on ARP Pro Series head bolts for their all out competition engines. Simply stated, there's not a better bolt setup on the market today. ARP uses a premium grade 8740 alloy that is rated far superior to ﾓaircraftﾔ quality. Each bolt is placed vertically in special racks and precisely heat-treated to 200,000 psi. Following heat-treat, each bolt is centerless ground to make it as close to perfectly concentric as possible. This procedure involves about ten very slight cuts and results in an exceptionally straight part.